Trim panels are normally manufactured by means of hot and cold forming of a laminate consisting of several sheets or layers.
The trim consists of two main parts, one structural part called a substrate, which makes it self-supporting, and at least one decorative outer part called a covering.
The decorative covering is applied to the visible face of the trim, i.e. the surface of the trim that the user sees and perceives when they are inside the vehicle.
Additionally, a second protective covering can be applied to the non-visible face to cover the substrate on the surface of the trim that corresponds with the bodywork of the vehicle or the surface that is not seen by the user.
The substrate normally consists of a central core, adhesive and a reinforcement material situated in correspondence with each of the upper and lower faces of the sheet, so that these three elements are what make the end product, which in this case is the trim panel, sufficiently rigid for the customers requirements.
The central core normally consists of a sheet of foam or a sheet of interwoven fibres. This central core can also be completely or partially impregnated with a resin in order to make the sheet more rigid.
The reinforcement material that is applied to the upper and lower faces of the sheet that forms the central core can take the form of a chopped-fibre roving or mat.
In any case, the use of fibre reinforcement as an additional component to the central core is necessary to achieve the levels of rigidity and self-support required by the customer for this product.
Fibre reinforcement and fibreglass, in particular, is a material that causes many handling problems in a production line. Fibreglass is abrasive to the production facilities and harmful to the operators who handle it.
The problem with fibreglass can be lessened by using a different type of fibre, such as natural fibres. This type of fibres does not always achieve the required levels of rigidity and in any case they are an additional part to handle when manufacturing the trim panel.
Examples of this type of trim manufacturing process can be found in American patents U.S. Pat. Nos. 5,976,646 and 5,486,256.
In order to overcome above inconvenient, it is known from EP0711808, a method for manufacturing vehicle trim panels, wherein the number of independent components to be used for the manufacturing thereof is reduced. This procedure is based on the incorporation of the reinforcement fibre as integral part of the sheet of foam which forms the central core of the vehicle trim panel.
Although this procedure simplifies, reduces costs and improves the health and safety conditions of the manufacturing process, it does not carry out a control of the reinforcement fibre distribution in the sheet of foam in order to achieve a sheet of foam with optimal features of rigidity.
Therefore, present invention consists of a procedure for obtaining a vehicle trim panel wherein the central core of the panel incorporates reinforcement fibre as integral part of it and wherein rigidity properties of the sheet of foam have been improved by controlling the reinforcement fibre distribution in said sheet of foam.